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Direct and maternal genetic relationships between lamb live weight and carcass traits in Swedish sheep breeds.

Abstract

In Sweden, when not including subsidies, meat production accounts for 60 - 90 % of income from the sheep enterprise. Sheep farmers are paid for weight of carcass and according to carcass fleshiness and fatness grades. In the Swedish Sheep Recording Scheme (SSRS) selection of ewes and rams is based on a selection index considering lamb live weight at around four months, ewe fertility and for Gotland lambs also fleece quality. Furthermore, rams used as sires are evaluated using a BLUP animal model (Näsholm, 1999). Until recently, only 4-month weight (4MW) and fleece quality were included in the BLUP-evaluations. For an efficient and profitable production it is also important to breed for improved carcass quality. Both in Denmark and Norway carcass data from commercial slaughterhouses are included in the genetic evalutations of sheep (Pedersen, 1993 ; Olesen et al., 1995). To include carcass traits also in the Swedish BLUP-evaluations information on genetic parameters for these traits and their genetic relationships with 4MW are needed. In this study data from the BLUPevaluations in SSRS and commercial slaughterhouses were used. Heritabilities for carcass weight (CW), fleshiness (FLESH), and fatness (FAT) were estimated. Furthermore, genetic correlations between these traits and also the correlations with 4MW were calculated.